Many of society's most pressing problems can be related, either directly or indirectly, to behavioral predispositions having long phylogenetic histories, namely, aggression and violence (e.g. competitive violence between gangs, domestic violence) and sexual behavior (e.g. spread of AIDS, teenage pregnancies, sex offenders). The aims of the proposed studies are to continue a comprehensive psychobiological research program on brain function, behavior and mental health by investigating the behavioral, physiological and neuroendocrine mechanisms regulating male aggressive and sexual motivation in a social primate, the cynomolgus monkey. Experiment I will use well-established behavioral techniques (which prevent injuries) systematically to examine, for the first time in a primate, how aromatizable and non-aromatizable androgens affect different types of male aggression, specifically aggression directed at other males and aggression directed at the female partner. Experiment II and III are concerned with the behavioral effects and mechanisms of action of progestins, which are used clinically to treat sex offenders. Experiment II will investigate the behavioral and hormonal effects of progesterone, and will use high performance liquid chromatography to examine if it, like the synthetic progestin Depo-Provera, decreases androgen uptake by brain. Experiment III will use combined autoradiographic and immunocytochemical techniques to map the locations of androgen and progestin target neurons and receptors, and to differentiate between several possible mechanisms by which progestins may exert their inhibitory effects on androgen uptake in brain regions controlling male sexual motivation and behavior. Experiment IV will use dual-labeling immunocytochemical techniques with mated and unmated male and female monkeys to link sexual consummation to gonadal hormones at a neuronal level by identifying androgen and progestin receptor-containing neurons that also express the products of the early immediate gene c-for. Comparisons between monkeys and rats will help elucidate a previously identified species difference in mating-induced c-fos expression.